I do buff the blank before assembly.I also like to give it a quick final buff after assembly.I did a test and buffed a rhodium trimline, both clip and again on the nib.I held it in one place for 1 minute.The plating showed no wear.
I thought rhodium was rhodium,one wears off easily, the other impervoius.What gives?
Welcome to the wild world of pen purchasing.
NO, what one company calls rhodium is not necessarily what another calls rhodium. There is no industry standard, as we found out some years ago when we learned "Germany" did not mean 'MADE in Germany' when used on a fountain pen nib. Oh, and "iridium" should not be taken to mean there is actually iridium anywhere NEAR the nib.
Some companies have made pen kits for years. They have a track record of honesty. Others are newer and have "borrowed" the earlier company's kit names and have mimicked the names of the platings. You might find that some "gold" kits have no gold.
Unless you have lots of time with nothing to do, pick a vendor you trust and let HIM do the homework. Unlike the jewelry industry, there is no "standard" upon which you can rely.